Those are remnants of the registration marks found on the proofs.
Originally there would be one on each border for each color. They help lay out the plates if it's being done by transfers as I believe it was. Then the marks are erased. If they're not erased completely there will be a mark. Usually just the small ones, but once in a while there's a larger mark leftover.
Here's two different Batch cards, one with what looks like just black and blue marks, the other with black, blue and pink.
I have a Cravath with a good sized remnant in red on the right side, but I haven't scanned it yet.
Steve B